For a time, the best candidate for the "real" Resurrection Mary was Mary Miskowski.
According to witness accounts Troy Taylor, my colleague from my time with Weird Chicago, gathered very recenty, Mary Miskowski died on or around Halloween, 1930, at the age of 18 or 19, having been hit by a car on 47th street while going to a Halloween party, at which she was dressed as a bride in her mother's old wedding dress. A blonde herself, she would have matched the traditional description of Mary - a teenage blonde girl in a white dress - far better than most other canditates (Mary Bregovy was a brunette, and Anna Norkus wasn't quite 13).
Finding solid information about Mary Miskowski was tough - Troy's best information came from a woman whom Mary used to babysit. Variant spellings of her name make it hard to pin down records about her. Here, though, is a census record of her family that would have been taken shortly before her death in 1930. Mary was said to live at 4924 S. Damen - according to the Ward maps from 1930, this census record came from exactly the right block.
This backs up the stories Troy was told indicating that she was old enough to be on her own, but still living with her family. The census shows that she was living at home at age 19.
Stories of her death, however, were harder to verify - no Mary Miskowsky (or Miskowski) is listed as dying in Illinois between 1916 and 1950 in the Illinois Death Index. When I started digging into the files, I half suspected it would be one of those times where it turns out the subject not only didn't die in 1930, but still hasn't died yet - or, at least, didn't die until a few years back.
The death index lists a Mary Muchowksi as dying on November 5, 1930 - people familiar with digging through census records and stuff will know that for a record for "Miskowski" written in cursive to be typed in as Muchowski would hardly be unlikely (especially if they forgot to dot the i - just look at it above).
November 5 would be a few days after Halloween, but pretty close to it, as well. Her death does not appear to have made the papers, as Mary Bregovy and Anna Norkus's did, though, which may be why it wasn't until the recent stories have come to light that her name has been considered seriously as a candidate.
Research by Ray Johnson, the Haunt Detective has now indicated that the name in the records was not a misprint, and that a woman named Mary Muchowski, age 67, really did die that day, which left the fate of the Mary Miskowski above an open question for some time.
One woman in Chicago named Mary Miskowsky married a man named Roy Jensen in 1937. THAT Mary Miskowski died just a few years back, but her parents' names were not John and Helen, indicating that she's not the Mary Miskowsky from the 1930 census.
New information added here December 2011: The fate of the Mary Miskowsky in the census has now been solved - according to a couple of obituaries (hers and her father's, from 1963), Mary Miskowsky married a man named John Sutko, with whom she had three children, and died in 1956. She was interred at Evergreen; John died in 2003.
This DOES raise another question - why did the woman (and her cousins) so vividly remember Mary Miskowksy of S. Damen dying in 1930? Were they mistaking her for someone else? There were a number of car accidents around that time, including a boy who was hit by a car and killed on the 5400 block of S. Damen on October 30, 1930, not far away from Mary Miskowsky's house. The funeral record book that contains Anna Norkus's funeral information also lists a funeral for a young man who was murdered in 1929 barely a block from Mary Miskowsky's house.
Here's Mary's obit from 1956. The parents and siblings listed here match the ones in the 1930 census exactly:
I've blocked out a few names because I tend to get really unpleasant emails about Resurrection Mary and don't wish for her surviving family to be hassled. The names of her kids and her sisters' married names aren't really relevant here. In any case, this firmly establishes that at the time of Mary Miskowsky's death, she was much older than the ghost is said to be, and she was interred at Evergreen, not Resurrection, and can be eliminated as a candidate. No cause of death is listed, but she would have been 45 years old, and was certainly not killed en route to a costume party in 1930.
For a whole lot more information, check out our Resurrection Mary Roundtable podcast episode!